#3272 swamp-extensions: use explicit npm:/jsr: specifiers in root extensions/models

Follow-up to swamp-club #3114. The root extensions/models copy that the verification workflows run (issue_lifecycle.ts, _lib/schemas.ts, review_record.ts import zod; _lib/swamp_club.ts imports @std/path) still uses bare import-map names. It is unpublished, so the registry never scores it, but first-party code is what authors copy.

The rewrite was dropped from #3114's PR #468: extensions/models/ is a trust-root path, so touching it triggers CI's Review Integrity audit, which currently stalls in the runner (Lab #3174).

Expected: replace each bare import with its target from the root deno.json import map (npm:zod@4.3.6, jsr:@std/path@1). Best done after #3174 is fixed, so the trust-root audit can review it.